Rotor for wound field electric motor and wound field electric motor

Abstract

This rotor for a wound field electric motor comprises: an annular rotor core that has a plurality of circumferential direction coil slots formed at intervals along the circumferential direction; and a circumferential coil that is wound around the rotor core along the cirucmferential direction on an axial-direction end surface of the rotor core, by way of adjacent circumferential direction coil slots. The rotor core has radial direction coil slots including an inner-circumferential-side slot and an outer-circumferential-side slot formed along the radial direction between poles formed by the circumferential coil, and a radial-direction coil is comprised which is wound around the rotor core along the radial direction on an axial-direction end surface of the rotor core, by way of the radial-direction coil slots.

Description

Rotor for wound field type electric motor and wound field type electric motor

[0001] The present invention relates to a rotor for a wound-field motor and a wound-field motor, and more particularly to a rotor for a wound-field motor that can realize a Halbach array that can contribute to improving magnetic force, and a wound-field motor including the same.

[0002] Patent Document 1 discloses a rotor for a wound-field synchronous machine that can simplify assembly work and significantly suppress increases in manufacturing costs. This rotor for a wound-field synchronous machine includes a rotatably supported rotating shaft, a rotor core coaxially fitted to the rotating shaft, and a field winding attached to the rotor core, in which the rotor core includes an annular outer peripheral portion, a plurality of teeth that protrude radially inward from the inner surface of the outer peripheral portion and are formed integrally with the outer peripheral portion at specified intervals around the circumferential direction of the outer peripheral portion, and each of which has a field winding attached thereto, and tooth engaging portions that are formed integrally with the teeth, and the rotating shaft engages with the tooth engaging portions of the rotor core.

[0003] Japanese Patent Application Publication No. 2020-188637

[0004] However, Patent Document 1 merely discloses that, in order to simplify assembly and significantly suppress increases in manufacturing costs, a field winding wound around a bobbin or the like is fitted into the teeth of the rotor core from the radially inner side. Therefore, a wound-field synchronous machine equipped with a rotor such as that disclosed in Patent Document 1 has the problem of not being sufficient to achieve the further performance improvements required of wound-field electric motors.

[0005] The present invention has been made in consideration of the problems associated with the conventional technology, and has an object to provide a rotor for a wound-field type electric motor that can realize a Halbach arrangement that can contribute to improving magnetic force, and a wound-field type electric motor equipped with the same.

[0006] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that the above-mentioned object can be achieved by configuring a rotor for a wound-field type electric motor with a circumferential coil, in which the rotor core has radial coil slots including inner and outer slots formed along the radial direction between the poles formed by the circumferential coil, and the rotor core has radial coils wound along the radial direction at its axial end faces via the radial coil slots, thereby completing the present invention.

[0007] That is, the rotor for a wound-field electric motor of the present invention comprises an annular rotor core having a plurality of circumferential coil slots formed at intervals along the circumferential direction, and circumferential coils wound circumferentially around the rotor core at its axial end face via adjacent circumferential coil slots. The rotor core has radial coil slots including inner and outer slots formed radially between poles formed by the circumferential coils, and the rotor core comprises radial coils wound radially around the rotor core at its axial end face via the radial coil slots.

[0008] Furthermore, the present invention provides a wound-field electric motor comprising an annular stator and a rotor for a wound-field electric motor arranged inside the stator. The rotor for a wound-field electric motor comprises an annular rotor core having a plurality of circumferential coil slots formed at intervals along the circumferential direction, and circumferential coils wound circumferentially around the rotor core at its axial end face via adjacent circumferential coil slots. The rotor core has radial coil slots including inner and outer slots formed radially between poles formed by the circumferential coils, and the rotor core comprises radial coils wound radially around the rotor core at its axial end face via the radial coil slots.

[0009] According to the present invention, in a rotor for a wound-field type electric motor equipped with a circumferential coil, the rotor core has radial coil slots including inner and outer slots formed along the radial direction between the poles formed by the circumferential coil, and the rotor core is equipped with radial coils wound along the radial direction at its axial end face via the radial coil slots. Therefore, it is possible to provide a rotor for a wound-field type electric motor that can realize a Halbach arrangement that can contribute to improving magnetic force, and a wound-field type electric motor equipped with the same.

[0010] FIG. 1 is an explanatory diagram schematically showing a first embodiment of a wound-field motor of the present invention; FIG. 2 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor shown in FIG. 1; FIG. 3 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of a second embodiment; FIG. 4 is an explanatory diagram schematically showing a third embodiment of a wound-field motor of the present invention; FIG. 5 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor shown in FIG. 3; FIG. 6 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of a fourth embodiment; FIG. 7 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of a fifth embodiment; FIG. 8 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of a sixth embodiment; FIG. 9 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of a seventh embodiment; FIG. 11 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of an eighth embodiment; and FIG. 12 is an explanatory diagram schematically showing a portion of a rotor for a wound-field motor of a ninth embodiment.

[0011] The rotor for a wound-field motor and the wound-field motor of the present invention will be described in detail below with reference to the drawings. Note that in the following description, the "rotor for a wound-field motor" may be simply referred to as the "rotor." Also, the dimensional proportions in the drawings cited below are exaggerated for the sake of explanation and may differ from the actual proportions.

[0012] First Embodiment FIG. 1 is a schematic diagram illustrating a wound-field motor according to a first embodiment, showing a cross section of the rotor for the wound-field motor in a direction parallel to the rotor shaft. As shown in FIG. 1, the wound-field motor 1 of this embodiment includes a rotor shaft 10, a rotor 20 for the wound-field motor, a stator 30, and a housing 40. The rotor 20 includes an annular rotor core 21 and a coil 23 wound around the rotor core 21, and is integrally formed on the outer periphery of the rotor shaft 10. The rotor shaft 10 is fixed, for example, by press-fitting into the inner diameter of the rotor 20. The rotor core 21 may be a conventional rotor core formed by laminating electromagnetic steel sheets. The coil 23 may be, for example, a round wire coil or a rectangular wire coil. For example, when the rotor core is an integrated rotor core as shown in FIG. 2, the coil is preferably, for example, a U-shaped rectangular wire coil. Such U-shaped rectangular wire coils can be wound around a rotor core by inserting multiple rectangular wire coils into slots and joining their ends. When the rotor core is an integrated rotor core as shown in FIG. 2 or a split rotor core (see FIG. 5) as described below, either round or rectangular wire coils may be used. The stator 30 is annular and is arranged around the rotor 20 with a gap G provided around the rotor 20. The housing 40 accommodates the rotor 20 and rotatably supports the rotor shaft 10 via ball bearings 41, and also accommodates and fixes the stator 30. A suitable example of such a wound-field motor is a wound-field synchronous motor.

[0013] The upper view of Fig. 2 is a plan view schematically showing a 120° portion of the rotor for the wound-field motor shown in Fig. 1, and the lower view of Fig. 2 is a cross-sectional view perpendicular to the rotor shaft schematically showing a 120° portion of the rotor for the wound-field motor shown in Fig. 1. The rotor for the wound-field motor also has a similar structure in the remaining 240° portion of the rotor for the wound-field motor, which is not shown in Fig. 2. In the lower view of Fig. 2, a black circle within a circle indicates that current is flowing in the direction from the back to the front of the page, and a cross within a circle indicates that current is flowing in the direction from the front to the back of the page.

[0014] As shown in FIG. 2 , the rotor 20 of the first embodiment includes an annular rotor core 21 having a plurality of circumferential coil slots 21 a ( 21 a 1, 21 a 2, 21 a 3) spaced apart along the circumferential direction, and circumferential coils 23A ( 23A 1, 23A 2) wound around the axial end face of the rotor core 21 in the circumferential direction via adjacent circumferential coil slots 21 a ( 21 a 1 and 21 a 2, and 21 a 2 and 21 a 3 in FIG. 2 ). Here, "the circumferential coil is wound around the axial end face of the rotor core in the circumferential direction" includes not only the case where the circumferential coil is wound completely around the circumferential direction at the axial end face of the rotor core, but also the case where the circumferential coil is wound linearly between the circumferential coil slots at the axial end face of the rotor core. Furthermore, these circumferential coil slots 21 a penetrate the rotor core 21 in the axial direction. Furthermore, these circumferential coils 23A are arranged continuously in the circumferential direction on the axial end surface of the rotor core 21 (see the upper view in FIG. 2).

[0015] The rotor core 21 has radial coil slots 21r, including inner slots 21i (21i2) and outer slots 21o (21o2), formed along the radial direction between poles formed by the circumferential coils 23A1 and 23A2, respectively. The rotor core 21 also has radial coils 23B (23B2) wound along the radial direction at the axial end face of the rotor core 21 via the radial coil slots 21r (inner slots 21i2, outer slots 21o2). Here, "pole" refers to an electromagnet formed by supplying current to the circumferential coil. Furthermore, "radial coils wound along the radial direction at the axial end face of the rotor core" includes not only cases where the radial coils are wound completely along the radial direction at the axial end face of the rotor core, but also cases where the radial coils are wound linearly between the radial coil slots at the axial end face of the rotor core. Furthermore, these radial coil slots 21r also penetrate the rotor core 21 in the axial direction. The circumferential coil 23A and the radial coil 23B may partially overlap each other.

[0016] The rotor core 21 also has a radial coil 23B1 wound radially around the axial end face of the rotor core 21 via the inner slot 21i1 and the outer slot 21o1, and a radial coil 23B3 wound radially around the axial end face of the rotor core 21 via the inner slot 21i3 and the outer slot 21o3.

[0017] Next, the advantages of this embodiment will be described. According to this embodiment, in a rotor 20 equipped with circumferential coils 23A, the rotor core 21 has radial coil slots 21r, including inner slots 21i2 and outer slots 21o2, formed along the radial direction between the poles formed by the circumferential coils 23A. The rotor core 21 also has radial coils 23B2 wound along the radial direction on the axial end face of the rotor core 21 via the radial coil slots 21r (the inner slots 21i2 and the outer slots 21o2). This allows for a Halbach array that can contribute to improved magnetic force, even though the rotor is for a wound-field motor. Note that the arrows in the lower diagram of FIG. 2 represent magnetic field lines. This allows for improved torque and a more compact wound-field motor.

[0018] 3 to 11 are explanatory diagrams showing schematic diagrams of other embodiments of a rotor for a wound-field type electric motor and a wound-field type electric motor. In the following description, the same components as those described in each embodiment are designated by the same reference numerals, and detailed descriptions of the invention are omitted.

[0019] Second Embodiment The upper view of FIG. 3 is a plan view schematically showing 120° of a portion of the rotor for a wound-field electric motor of the second embodiment used in the wound-field electric motor of the second embodiment, and the lower view of FIG. 3 is a cross-sectional view in a direction perpendicular to the rotor shaft, schematically showing 120° of a portion of the rotor for a wound-field electric motor of the second embodiment.

[0020] As shown in FIG. 3, the rotor 20A of the second embodiment has a structure similar to that of the rotor 20 of the first embodiment, except that the circumferential coils 23A (23A1, 23A2) are arranged intermittently in the circumferential direction on the circumference of the axial end face of the rotor core 21 (see the upper view of FIG. 3), and the radial coils 23B (23B2) are arranged circumferentially between the circumferential coils 23A (in FIG. 3, the circumferential coils 23A1 and 23A2).

[0021] More specifically, the rotor 20A includes an annular rotor core 21 having a plurality of circumferential coil slots 21a (21a1, 21a2, 21a3, 21a4) spaced apart along the circumferential direction. The circumferential coils 23A (23A1, 23A2) are wound around the rotor core 21 along the circumferential direction at its axial end face via adjacent circumferential coil slots 21a (in FIG. 3, the circumferential coil slots 21a1 and 21a2, and the circumferential coil slots 21a3 and 21a4).

[0022] Next, the advantages of this embodiment will be described. According to this embodiment, since the circumferential coils 23A and the radial coils 23B are arranged as described above, in addition to the advantages of the first embodiment, there is an advantage that the circumferential coils and the radial coils can be prevented from overlapping with each other on the axial end surface of the rotor core.

[0023] <Third embodiment> Fig. 4 is an explanatory diagram schematically showing a wound-field electric motor of a third embodiment, and is a cross-sectional view in a direction parallel to the rotor shaft of a rotor for a wound-field electric motor. The upper view of Fig. 5 is a plan view schematically showing 120° of a portion of the rotor for a wound-field electric motor of the third embodiment used in the wound-field electric motor of the third embodiment, and the lower view of Fig. 5 is a cross-sectional view in a direction perpendicular to the rotor shaft schematically showing 120° of a portion of the rotor for a wound-field electric motor of the third embodiment.

[0024] As shown in Figures 4 and 5, the wound-field motor 3 of this embodiment has the same structure as the wound-field motor 1 of the first embodiment, except that the rotor 20B further includes an annular retaining member 25, the rotor core 21 is formed by circumferentially dividing the rotor core 21 into split rotor cores 211, 212 which are connected in the circumferential direction, and each of the split rotor cores 211, 212 includes a circumferential coil 23A and a radial coil 23B.

[0025] More specifically, the rotor 20B includes an annular rotor core 21 having a plurality of circumferential coil slots 21a (21a1, 21a2, 21a3) spaced apart along the circumferential direction. The circumferential coils 23A (23A1, 23A2) are wound around the rotor core 21 along the circumferential direction at its axial end face via adjacent circumferential coil slots 21a (in FIG. 5 , the circumferential coil slots 21a1 and 21a2, and the circumferential coil slots 21a2 and 21a3). The circumferential coil slots 21a2 are formed in both the split rotor cores 211 and 212. In FIG. 5 , the circumferential coil slots 21a2 formed in both the split rotor cores 211 and 212 are connected to each other. On the other hand, although not shown, the circumferential coil slots 21a2 formed in both the split rotor cores 211 and 212 may not be connected (not shown). Furthermore, the split rotor core 211 has radial coils 23B (23B1, 23B2) at both circumferential ends, and the split rotor core 212 has radial coils 23B (23B2, 23B3) at both circumferential ends. Furthermore, when the rotor shaft 10 is press-fitted and fixed to the inner diameter side of the rotor core 21 (rotor 20) formed by connecting the split rotor cores 211 and 212 circumferentially, the retaining member 25 holds down the split rotor cores 211 and 212 from their outer diameter sides. A suitable example of such a retaining member is an annular carbon fiber reinforced resin part made of carbon fiber reinforced resin or the like. While the split rotor cores 211 and 212 are preferably obtained from the same rotor core, they may also be obtained from different rotor cores.

[0026] Next, advantages of this embodiment will be described. According to this embodiment, even if the rotor core 21 is formed of the split rotor cores 211, 212 as described above, the same advantages as those of the first embodiment can be obtained. Another advantage is that it is easy to wind coils around the split rotor cores.

[0027] <Fourth embodiment> The upper view of Fig. 6 is a plan view showing a schematic view of 120° that is a portion of the rotor for a wound-field type electric motor of the fourth embodiment used in the wound-field type electric motor of the fourth embodiment, and the lower view of Fig. 6 is a cross-sectional view in a direction perpendicular to the rotor shaft that shows a schematic view of 120° that is a portion of the rotor for a wound-field type electric motor of the fourth embodiment.

[0028] As shown in Figure 6, the rotor 20C of the fourth embodiment has a structure similar to that of the rotor 20B of the third embodiment, except that the split rotor core 211 has a radial coil 23B (23B1) at one end in the circumferential direction, and the split rotor core 212 also has a radial coil 23B (23B2) at one end on the same side in the circumferential direction.

[0029] Next, the advantages of this embodiment will be described. According to this embodiment, even if the rotor core 21 is formed of the divided rotor cores 211 and 212 as described above, the same advantages as those of the third embodiment can be obtained.

[0030] Fifth Embodiment The upper view of FIG. 7 is a plan view schematically showing 120° of a portion of a rotor for a wound-field electric motor of the fifth embodiment used in the wound-field electric motor of the fifth embodiment, and the lower view of FIG. 7 is a cross-sectional view in a direction perpendicular to the rotor shaft, schematically showing 120° of a portion of the rotor for a wound-field electric motor of the fifth embodiment.

[0031] As shown in Figure 7, the rotor 20D of the fifth embodiment further includes an annular retaining member 25, and the rotor core 21 is formed by circumferentially dividing the rotor core 21 into split rotor cores 211, 212, which are connected in the circumferential direction, and each of the split rotor cores 211, 212 includes either a circumferential coil 23A or a radial coil 23B, and the split rotor cores 212 including the circumferential coil 23A and the split rotor cores 211 including the radial coil 23B are arranged alternately in the circumferential direction, except that the rotor 20D has the same structure as the rotor 20 of the first embodiment.

[0032] More specifically, the split rotor core 212 has a plurality of circumferential coil slots 21a (21a1, 21a2, 21a3, 21a4) formed at intervals along the circumferential direction, and the circumferential coils 23A (23A1, 23A2) are wound around the split rotor core 212 in the circumferential direction at its axial end face via adjacent circumferential coil slots 21a (in Figure 7, circumferential coil slots 21a1 and 21a2, and circumferential coil slots 21a3 and 21a4). In addition, the split rotor core 211 has radial coil slots 21r including inner slots 21i (21i1, 21i2) and outer slots 21o (21o1, 21o2) formed along the radial direction, and the radial coils 23B (23B1, 23B2) are wound around the split rotor core 211 via the radial coil slots 21r (inner slots 21i, outer slots 21o).

[0033] Next, advantages of this embodiment will be described. According to this embodiment, even if the rotor core 21 is formed of the split rotor cores 211, 212 as described above, in addition to the advantages of the first embodiment, there is an advantage that overlapping of the circumferential coil and the radial coil at the axial end face of the rotor core can be suppressed. Another advantage is that coils can be easily wound in the split rotor cores. More specifically, by providing a split rotor core with a coil wound in the circumferential direction and a split rotor core with a coil wound in the radial direction, and by alternately connecting the split rotor cores with the circumferential coil wound and the split rotor cores with the radial coil wound around them in the circumferential direction, the split rotor cores can be easily wound with coils.

[0034] Sixth Embodiment The upper view of FIG. 8 is a plan view schematically showing 120° of a portion of a rotor for a wound-field electric motor of the sixth embodiment used in the wound-field electric motor of the sixth embodiment, and the lower view of FIG. 8 is a cross-sectional view in a direction perpendicular to the rotor shaft, schematically showing 120° of a portion of the rotor for a wound-field electric motor of the sixth embodiment.

[0035] As shown in FIG. 8, the rotor 20E of the sixth embodiment has a structure similar to that of the rotor 20B of the third embodiment, except that the number of turns of the radial coil 23B (23B2) is smaller than the number of turns of the circumferential coil 23A (23A1).

[0036] Next, advantages of this embodiment will be described. According to this embodiment, even if the rotor core 21 is formed of the split rotor cores 211, 212 as described above, the same advantages as those of the third embodiment can be obtained. In particular, when the split rotor core 211 is provided with radial coils 23B (23B1, 23B2) at both circumferential ends thereof and the split rotor core 212 is provided with radial coils 23B (23B2, 23B3) at both circumferential ends thereof, a double configuration is achieved at the location where the radial coil 23B (23B2) is arranged. Therefore, by making the number of turns of the radial coil less than the number of turns of the circumferential coil, an appropriate coil configuration can be achieved. Furthermore, by reducing the number of turns of the radial coil, a larger area can be secured for the circumferential coil, which has the advantage of allowing the coil length of the circumferential coil to be set to a large value.

[0037] Seventh Embodiment The upper view of FIG. 9 is a plan view schematically showing 120° of a portion of a rotor for a wound-field electric motor of the seventh embodiment used in the wound-field electric motor of the seventh embodiment, and the lower view of FIG. 9 is a cross-sectional view in a direction perpendicular to the rotor shaft, schematically showing 120° of a portion of the rotor for a wound-field electric motor of the seventh embodiment.

[0038] As shown in FIG. 9, the rotor 20F of the seventh embodiment has a structure similar to that of the rotor 20B of the third embodiment, except that the circumferential coil slots 21a (21a1, 21a2, 21a3) are formed radially between the inner slots 21i (21i1, 21i2, 21i3) and the outer slots 21o (21o1, 21o2, 21o3), and at positions closer to the outer slots 21o (21o1, 21o2, 21o3) than to the inner slots 21i (21i1, 21i2, 21i3).

[0039] Next, advantages of this embodiment will be described. In this embodiment, the circumferential coil slots 21a are formed at the above-described positions, and the circumferential coils 23A are disposed therein. The magnetic field lines between the circumferential coil slots 21a and the outer-periphery slots 21o may be opposite to the magnetic field lines between the circumferential coil slots 21a and the inner-periphery slots 21i due to the direction of current flowing through the nearby coils. According to this embodiment, by narrowing the gap between the circumferential coil slots 21a and the outer-periphery slots 21o, in addition to the advantages of the third embodiment, it is possible to suppress or prevent the occurrence of such a phenomenon and efficiently generate a magnetic field. Furthermore, magnetic field lines directed toward the stator (not shown) may be formed between the circumferential coil slots 21a and the inner-periphery slots 21i due to the direction of current flowing through the nearby coils. However, by widening the gap between the circumferential coil slots 21a and the inner-periphery slots 21i, it is possible to efficiently form the circumferential magnetic field lines.

[0040] Eighth Embodiment The upper view of FIG. 10 is a plan view schematically showing 120° of a portion of a rotor for a wound-field electric motor of the eighth embodiment used in the wound-field electric motor of the eighth embodiment, and the lower view of FIG. 10 is a cross-sectional view in a direction perpendicular to the rotor shaft, schematically showing 120° of a portion of the rotor for a wound-field electric motor of the eighth embodiment.

[0041] As shown in FIG. 10, the rotor 20G of the eighth embodiment has the same structure as the rotor 20B of the third embodiment, except that the circumferential coil slots 21a (21a1, 21a2, 21a3) and the outer peripheral slots 21o (21o1, 21o2, 21o3) are integrated in the radial direction to form integrated slots 21b.

[0042] Next, advantages of this embodiment will be described. In this embodiment, the circumferential coil slots 21 a and the outer peripheral slots 21 o are integrated to form an integrated slot 21 b. The magnetic field lines between the circumferential coil slots 21 a and the outer peripheral slots 21 o may be opposite to the magnetic field lines between the circumferential coil slots 21 a and the inner peripheral slots 21 i due to the direction of current flowing through the nearby coils. According to this embodiment, by forming the integrated slot 21 b described above, in addition to the advantages of the third embodiment, it is possible to suppress or prevent the occurrence of such a phenomenon and efficiently generate a magnetic field. Furthermore, magnetic field lines directed toward the stator (not shown) may be formed between the circumferential coil slots 21 a and the inner peripheral slots 21 i due to the direction of current flowing through the nearby coils. However, by widening the gap between the circumferential coil slots 21 a and the inner peripheral slots 21 i, it is possible to efficiently form circumferential magnetic field lines.

[0043] Ninth Embodiment The upper view of FIG. 11 is a plan view schematically showing 120° of a portion of a rotor for a wound-field electric motor of the ninth embodiment used in the wound-field electric motor of the ninth embodiment, and the lower view of FIG. 11 is a cross-sectional view in a direction perpendicular to the rotor shaft, schematically showing 120° of a portion of the rotor for a wound-field electric motor of the ninth embodiment.

[0044] 11 , the rotor 20H of the ninth embodiment has the same structure as the rotor 20F of the seventh embodiment, except that a low-permeability member 27 (or a gap 21c serving as a flux barrier) made of resin or the like having a lower magnetic permeability than the rotor core 21 is provided between the circumferential coils 23A (23A1, 23A2, 23A3) in the circumferential coil slots 21a (21a1, 21a2, 21a3) and the radial coils 23B (23B1, 23B2, 23B3) in the outer-periphery slots 21o (21o1, 21o2, 21o3) in the radial direction. Although not shown, either or both of the low-permeability member and the gap may be interposed between the circumferential coils in the circumferential coil slots and the radial coils in the outer-periphery slots.

[0045] Next, advantages of this embodiment will be described. According to this embodiment, the low-permeability member 27 or the gap 21c, which has a lower magnetic permeability than the rotor core 21, is provided between the circumferential coil 23A in the circumferential coil slots 21a and the radial coil 23B in the outer slots 21o. In addition to the advantages of the seventh embodiment, this embodiment has the advantage of suppressing or preventing the occurrence of a phenomenon in which the magnetic field lines between the circumferential coil slots 21a and the inner slots 21i are directed in the opposite direction, thereby enabling efficient generation of a magnetic field.

[0046] Although the present invention has been described above with reference to some embodiments, the present invention is not limited to these, and various modifications are possible within the scope of the gist of the present invention.

[0047] In the present invention, in order to realize a Halbach arrangement that can contribute to improving magnetic force, a rotor for a wound-field type electric motor having circumferential coils is configured such that the rotor core has radial coil slots including inner and outer slots formed along the radial direction between the poles formed by the circumferential coils, and radial coils are wound along the radial direction on the axial end faces of the rotor core via the radial coil slots.

[0048] Therefore, although the sixth to ninth embodiments have been described above with reference to examples in which rotor core 21 is made up of split rotor cores 211, 212, the present invention is not limited to this. For example, rotor core 21 may be made up of an integrated rotor core.

[0049] In the above-described ninth embodiment, the circumferential coil slots 21 a are formed between the inner slots 21 i and the outer slots 21 o in the radial direction and closer to the outer slots 21 o than the inner slots 21 i. However, the present invention is not limited to this. In the present invention, the circumferential coil slots 21 a may be formed, for example, closer to the inner slots 21 i than the outer slots 21 o, or in an intermediate position between the outer slots 21 o and the inner slots 21 i.

[0050] Furthermore, for example, the above-mentioned components are not limited to the configurations shown in each embodiment, and it is possible to change the specifications and materials of the rotor core, coil, retaining member, and low magnetic permeability member in detail, or to combine and apply the components of one embodiment with the components of another embodiment.

[0051] 1, 3 Wound-field type electric motor 10 Rotor shaft 20, 20A to 20H Rotor for wound-field type electric motor 21 Rotor core 211, 212 Divided rotor core 21a Circumferential coil slot 21b Integrated slot 21c Air gap 21i Inner peripheral slot 21o Outer peripheral slot 21r Radial coil slot 23 Coil 23A Circumferential coil 23B Radial coil 25 Holding member 27 Low magnetic permeability member 30 Stator 40 Housing 41 Ball bearing G Gap

Claims

1. A rotor for a wound-field type electric motor comprising an annular rotor core having a plurality of circumferential coil slots formed at intervals along the circumferential direction, and circumferential coils wound circumferentially around the axial end face of the rotor core via adjacent circumferential coil slots, wherein the rotor core has radial coil slots including inner and outer slots formed along the radial direction between poles formed by the circumferential coils, and a radial coil is wound radially around the axial end face of the rotor core via the radial coil slots.

2. The rotor for a wound field type electric motor according to claim 1, characterized in that the rotor core is formed by circumferentially connecting split rotor cores, each of which is equipped with the circumferential coil and the radial coil.

3. A rotor for a wound field type electric motor as claimed in claim 1, characterized in that the circumferential coils are arranged intermittently in the circumferential direction on a circumference at the axial end face of the rotor core, and the radial coils are arranged between the circumferential coils in the circumferential direction.

4. The rotor for a wound field type electric motor as described in claim 1, characterized in that the rotor core is formed by circumferentially connecting split rotor cores obtained by dividing the rotor core in the circumferential direction, each of the split rotor cores having either the circumferential coil or the radial coil, and the split rotor cores having the circumferential coil and the split rotor cores having the radial coil are arranged alternately in the circumferential direction.

5. A rotor for a wound field type electric motor according to claim 2, characterized in that the number of turns of said radial coil is smaller than the number of turns of said circumferential coil.

6. A rotor for a wound field type electric motor as described in any one of claims 1 to 5, characterized in that the slots for the circumferential coils are formed in a position radially between the inner slots and the outer slots, and closer to the outer slots than the inner slots.

7. A rotor for a wound field type electric motor as claimed in any one of claims 1 to 5, characterized in that the circumferential coil slots and the outer peripheral slots are integrated to form integrated slots.

8. A rotor for a wound field type electric motor as described in claim 6, characterized in that a low permeability material with a magnetic permeability lower than that of the rotor core or an air gap is provided between the circumferential coil in the circumferential coil slot and the radial coil in the outer peripheral slot.

9. A rotor for a wound field type electric motor as described in claim 7, characterized in that a low permeability material with a magnetic permeability lower than that of the rotor core or an air gap is provided between the circumferential coil in the circumferential coil slot and the radial coil in the outer peripheral slot.

10. A wound-field type motor comprising an annular stator and a rotor for a wound-field type motor arranged inside the stator, wherein the rotor for a wound-field type motor comprises an annular rotor core having a plurality of circumferential coil slots formed at intervals along the circumferential direction, and a circumferential coil wound circumferentially around the rotor core at its axial end face via adjacent circumferential coil slots, and the rotor core has radial coil slots including inner and outer slots formed along the radial direction between poles formed by the circumferential coil, and a radial coil wound radially around the rotor core at its axial end face via the radial coil slots.